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Re: Reading portions of large files
From: |
David Kastrup |
Subject: |
Re: Reading portions of large files |
Date: |
11 Jan 2003 11:42:12 +0100 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.3.50 |
"Eli Zaretskii" <eliz@is.elta.co.il> writes:
> > From: David Kastrup <dak@gnu.org>
> > Newsgroups: gnu.emacs.help
> > Date: 10 Jan 2003 21:51:49 +0100
> >
> > BTW, would it be terribly complicated to extend the range of Lisp
> > integers to 31bit?
>
> It's not terribly hard, but IIRC the current consensus among the Emacs
> maintainers is that it's not important enough to do that because
> before long all machines will have 64-bit compilers.
>
> Perhaps this should be discussed again on the developers' list.
>
> > Integers don't need any garbage collection or tag bits per se.
>
> They need to be distinguishable from other Lisp types, so their tag
> bitfield cannot have an arbitrary bit pattern.
Yes, but a single bit is sufficient for that distinction. This could
even speed up operations, since the sign bit is a candidate that can
be rather quickly checked.
Something like
if (x < 0)
will establish that something is an integer,
(x + 0x40000000)
will yield the value of the integer, and
(x | 0x8000000)
will convert an integer back to a Lisp number.
I don't know whether an integer Lisp object needs to be identical to
an integer. If it does, then the above needs an offset of 0x40000000
everywhere, of course.
> > Emacs has a most-positive-fixnum of 134217727, while XEmacs has
> > 1073741823, more than 8 times as much. So it would appear to be
> > possible in theory.
>
> IIRC, the XEmacs way requires extensive changes in how Emacs works,
> but I don't remember the details.
No clue about that.
--
David Kastrup, Kriemhildstr. 15, 44793 Bochum
- Reading portions of large files, Gerald . Jean, 2003/01/09
- Re: Reading portions of large files, David Kastrup, 2003/01/09
- Re: Reading portions of large files, Eli Zaretskii, 2003/01/10
- Message not available
- Re: Reading portions of large files, Stefan Monnier <address@hidden>, 2003/01/13
- Re: Reading portions of large files, Miles Bader, 2003/01/13
- Re: Reading portions of large files, Miles Bader, 2003/01/13
- Re: Reading portions of large files, David Kastrup, 2003/01/13
- Re: Reading portions of large files, Miles Bader, 2003/01/13
- Re: Reading portions of large files, Lee Sau Dan, 2003/01/20
- Re: Reading portions of large files, Mac, 2003/01/24
- Re: Reading portions of large files, Stefan Monnier <address@hidden>, 2003/01/27
Re: Reading portions of large files, Eric Pement, 2003/01/10
Re: Reading portions of large files, Brendan Halpin, 2003/01/10